critical CVSS 10

CVE-2026-44329·Docker vulnerability

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without OAuth2/bearer-token authorization middleware. A network attacker who can reach SMF on the SBI can hit UPI endpoints with no Authorization header at all, and the requests reach the SMF business handlers. In the running Docker lab this was directly demonstrated for read (GET /upi/v1/upNodesLinks), write (POST /upi/v1/upNodesLinks with attacker-controlled UP-node and link payload), and delete (DELETE /upi/v1/upNodesLinks/{nodeID}) operations. This vulnerability is fixed in 4.2.2.

Severity
critical
Software
Docker
Fixed in
4.2.2
Published
2026-05-27

Affected versions

Until: 4.2.2

Fixed in: 4.2.2

How to fix this CVE

Update Docker to the latest version to ensure free5GC SMF components are patched. The vulnerability affects free5GC versions prior to 4.2.2, where the UPI management route group lacks proper OAuth2/bearer-token authorization. Upgrade Docker and verify that any containerized free5GC instances are running version 4.2.2 or later, which includes the authorization middleware fix.

sudo dnf upgrade docker-ce

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST|GET|DELETE /upi/v1/upNodesLinks[/^/]* HTTP/1\.1.*(?!Authorization|authorization|bearer|Bearer)

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement a WAF rule to require an Authorization header (bearer token or OAuth2 token) on all requests to /upi/v1/* endpoints. Block any request matching POST|GET|DELETE /upi/v1/ that lacks a valid Authorization header with HTTP 401 Unauthorized response.

How to check if you are affected

  1. Step 1: Check Docker version with `docker --version` and verify it is the latest stable release.
  2. Step 2: List running containers with `docker ps` and identify any free5GC SMF containers; note their image versions with `docker inspect <container_id> | grep -i version`.
  3. Step 3: Check container logs for unauthorized access attempts to UPI endpoints: `docker logs <container_id> | grep -i 'upi/v1' | grep -v 'Authorization'`.
  4. Step 4: Verify the SMF container is running free5GC 4.2.2 or later by executing `docker exec <container_id> cat /version.txt` or checking the image tag against your registry.

FAQ

What is CVE-2026-44329?

CVE-2026-44329 is a critical authorization bypass in free5GC's Service Mesh Function (SMF) where the UPI management route group is exposed without OAuth2 or bearer-token validation, allowing unauthenticated network attackers to read, modify, or delete user plane node configurations.

Is CVE-2026-44329 being actively exploited?

No, this vulnerability is not currently listed in CISA's Known Exploited Vulnerabilities catalog, and no public exploit code is available.

What versions of Docker are affected by CVE-2026-44329?

The vulnerability affects free5GC versions prior to 4.2.2 when running inside Docker containers. The Docker package itself is not directly vulnerable, but containers running vulnerable free5GC versions are at risk.

How do I check if my server is vulnerable to CVE-2026-44329?

Run `docker ps --format 'table {{.Image}}\t{{.Status}}'` to list containers, then for each free5GC SMF container, execute `docker inspect <container_id> | grep -i 'Image\|Version'` to verify the free5GC version is below 4.2.2.

Does Defensia detect CVE-2026-44329?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Docker is installed on a monitored server, CVE-2026-44329 will appear in your dashboard with remediation steps.

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References

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